Neighboring plants and core herbivores determine the importance of Swietenia macrophylla in the plant–herbivore network

Species contribute differently to the structure and stability of networks of interacting species. However, species contributions to the importance of other species is usually neglected, thus limiting our understanding of species dynamics beyond the general network structure. We combined knowledge on diversity effects on focal species and network ecology to analyze the influence of plants and herbivores on big-leaf mahogany's ( Swietenia macrophylla ) importance in the plant–herbivore network. To this end, we built interaction networks using information from a large-scale tree diversity experiment and performed computer simulations of species removal with redistribution of interactions. We compared the importance of big-leaf mahogany in the observed networks to simulated networks where we removed: (a) tree species with similar beetle assemblages to mahogany, (b) the most interconnected (core) tree species and (c) the core beetle species. Removal of the core and similar tree species increased the importance of mahogany, whereas eliminating core beetle species decreased it. Interestingly, the effect of core tree species on mahogany’s importance was mediated by core beetles ( R 2 = 0.46). Neither tree nor core beetle species’ effects were contingent on tree species richness or abundance. These results indicate that highly connected tree and herbivore species jointly determine the role of mahogany in the plant–herbivore network. Likewise, these results provide insight into the effect of tree species composition and highly interactive herbivores in shaping the role of species in the herbivore network.